Abstract: Objective To investigate the difference between younger adults and the elderly regarding the association of metabolically healthy obesity（MHO） with arterial stiffness. Methods Data were collected and analyzed from the health check-ups, outpatients and inpatients aged 30-95 years who carried out the measurement of carotid-femoral pulse wave velocity（cfPWV） and admitted to the Department of General Practice, Geriatrics and Cadre Ward of the First Affiliated Hospital of Fujian Medical University from February 2016 to December 2019. The elderly was defined as the chronological age of 65 or older. Elevated arterial stiffness was defined as cfPWV≥10 m/s. The Obesitywas defined as body mass index ≥25 kg/m~2. Metabolic unhealth was defined as having two and more components（excluding waist circumference） of metabolic syndrome based on the diagnostic criteria of the National Cholesterol Education Program Adult Treatment Panel Ⅲ（NECP-ATPⅢ）. According to obesity and the status of metabolic health, the subjects were divided into metabolically healthy non-obesity（MHNO）, MHO, metabolically unhealthy non-obesity（MUNO） and metabolically unhealthy obesity（MUO）. The difference was compared among the four groups, and multivariate logistic regression analysis was used to determine the association of obesity and metabolical unhealth with elevated arterial stiffness. Results A total of 3 355 subjects were included in this analysis. In younger adults, the detection rates of cfPWV was higher （8.62±1.59） vs（8.26±1.47） m/s, t=11.125, P=0.001and elevated arterial stiffness was more frequently observed in MHO than those in MHNO 18.12%（95%CI 16.54%-19.76%） vs 8.14%（95%CI 8.03%-9.26%）, χ~2=20.046, P＜0.001. In the elderly, there were no statistically significant differences in the level of cfPWV and detection rate of elevated arterial stiffness between MHNO and MHO（P＞0.05）. In both younger adults and the elderly, metabolic unhealth was observed to be associated with elevated arterial stiffness younger adults: OR=1.856（95%CI 1.413-2.440）, P＜0.001; the elderly: 1.519（95%CI 1.088-2.122）, P=0.014. Whereas, only in younger adults with metabolic health, obesity was found to be independently associated with elevated arterial stiffness OR=1.887（95%CI 1.189～2.993）, P=0.007. Furthermore, only in younger adults, MHO was shown to be correlated with elevated arterial stiffnessOR=2.249（95%CI 1.481-3.414）, P＜0.001. Conclusions There are differences between the younger adults and the elderly regarding the relationship between MHO and arterial stiffness. In younger adults, MHO is associated with elevated arterial stiffness; in the elderly, this association is not significant.